EXPERIMENT STATION BULLETINS. 529 



of the tubci-s in the form of small brownish, or when wet, iicinly l»la(k 

 spots, the tnbers should be soaked for not less than I/2 honr and II/2 will 

 do no harm in a solution of formaldehyde, forty per cent, used at the rate 

 of one pound or one pint to thirty gallons of water. This will destroy the 

 disease known as Scab. Formaldehyde can be secured of any druggist. 



If there is evidence of the Black Scurf, soak the uncut tubers in a solu- 

 tion of corrosive sublimate (bichloride of mercury), using four ounces 

 in four gallons of hot water, and when this is dissolved, add enough water 

 to make 30 gallons. Soak the seed for not less than I'o hour and li/o 

 hours will do no harm, but no longer. Use only wooden vessels for this 

 material. 



Corrosive sublimate is a deadly poison and should be kept away from 

 children and livestock. Do not use treated potatoes for eating purposes. 



When and How to Treat. The potatoes may be treated with either 

 material several weeks, if desired, befoi-e planting if care is taken nol 

 to re-infect the tubers by placing them in used sacks or crates which have 

 not been disinfected. Some growers prefer to treat just before planting. 

 The potatoes should be treated before the seed is cut. 



When only a few bushels of potatoes are to be treated they may be 

 placed in gunny sacks and submerged in a barrel fiom wliicli the head 

 has been removed. 



When large quantities are to be treated, a taid< should be provided Im 

 the purpose. The tank sliould be wide enough to allow two rows of 

 potato crates to be i)laced in it side by side and deep enough so the jxda- 

 toes, crates and all, can be submerged. It may be made any length dc 

 sired. As soon as the potatoes are treated, it is a good plan to suljuicrgr 

 them in clear water or to pour water over tluMii to prevent further action 

 of the material with which they are treated. If they are to be kepi 

 some time before they are planted, they should be spread out and dricil. 



For the Hlkmit am» "Bt(;s." Hrgin spraying wiili Uordeanx-mixtnrc 

 and poison when the ''bugs" tirst appear, or wlien the plants are abont 

 8 inches high, and repeat about every two weeks as long as the plants 

 are growing. Sju-ay often in wai 111. iiinggy weather; fewer sprayings arf* 

 necessary in dry weather. 



Use Hordeaux-mi.xture Hi po\inds copper sulphate and I or ."> pounds nl' 

 lime to 50 gallons of water, and put in tlie poison, about 1/0 pound of 

 Paris-green or - or :', ponnds of arsenate of lead paste, or Iialf as much 

 of the i»owder, or ''i ]Miniid of the ])owdei-ed jiisenate of calcium, or 1 

 cpiart of the stock s(dution of Ked/.ie niixtni-e. This ainoimt of Kedzie 

 mixture is e(piivalent to 1^- iioimd of Paris-green. Some growers prefer 

 to use even more than this. 



Dilute linu' sulpliui- is uot .is good as (lie I'.oide.i u\ nii\l in<' for pol:i 

 toes. 



Potato Anus. During wet summers and especially duiin;^ iliose thai 

 fcdlow cold, wet si)rings, the ])otato-louse is apt to appear. This i)otato- 

 louse is not such a <lit1icult insect to kill if one can only reach it witli a 

 spray. The ditHculty comes from the fact that it hides under the foliage 

 of the potato, and that the spray must be directed upward fr(»m beneath 

 in order to hit any large proportion of the lice. Several devices have 

 been made for bringing about this result. The spray most eflScient is the 



